The present invention relates to novel chalcone derivatives, which are intermediates for the production of hydroxychalcones, and also to processes for producing hydroxychalcones using such chalcone derivatives.
Chalcone series compounds include chalcone, which can be produced by Claisen condensation reaction of acetophenone, and benzaldehyde and derivatives of chalcone. These chalcone compounds are known to have various pharmacological activities.
For example, Japanese Patent Application (Kokai) No. Sho 60-178815 describes examples in which chalcone compounds are used as active ingredients of antitumor drugs. Also, there is reported in Japanese Patent Publication (Kokoku) No. Sho 48-8485 that isoliquiritigenin (or 4,2',4'-trihydroxychalcone) is contained in extract of licorice root, exhibits antiulcer activity and is used in the therapy of gastric ulcer. Furthermore, it is known that isoliquiritigenin has antiallergic activity and is effective for the therapy, treatment and prophylaxis of asthma, allergic dermatitis, allergic rhinitis, urticaria, food allergy, and the like (Japanese Patent Application (Kokai) No. Sho 62-2027212). It is also known that isoliquiritigenin is also effective as a drug for the therapy, treatment and prophylaxis of kidney diseases such as kidney lesion caused by antitumor drugs, acute nephritis, chronic nephritis, Rehpus nephritis, and the like, and effective as a drug for the therapy, treatment and prophylaxis of liver diseases such as liver lesion caused by antitumor drugs, acute hepatitis, chronic hepatitis and the like (WO87-7835).
It is already known that isoliquiritigenin can be produced by reacting 2,4-dihydroxyacetophenone with 4-hydroxybenzaldehyde under alkaline conditions according to the following reaction scheme. ##STR2##
However, the yield of isoliquiritigenin obtained by the above reaction is about 20%, and in addition, chalcone compounds having a hydroxyl group at the 2-position of the acetophenone skeleton are obtained generally in low yield. Therefore, improvement for increasing the yield of chalcone compounds has been desired.